Method of manufacturing a semiconductor device and apparatus therefor

ABSTRACT

A method of manufacturing a semiconductor device includes providing an apparatus (210, 510) having tabs (212, 214, 412, 414) for holding and separating semiconductor substrates wherein a first tab (212, 412) is different from a second tab (214, 414), using the first tab (212, 412) to support a semiconductor substrate (224) wherein the second tab (214, 414) does not support the semiconductor substrate (224), and exposing the semiconductor substrate (224) to a chemical to move the semiconductor substrate (224) towards the second tab (214, 414) without removing the semiconductor substrate (224) from the apparatus (210, 510).

BACKGROUND OF THE INVENTION

This invention relates, in general, to semiconductor devices, and moreparticularly, to apparati and methods for manufacturing semiconductordevices.

At a recent International Conference on Gallium Arsenide ManufacturingTechnology (ManTech), the two largest causes for semiconductor waferbreakage during semiconductor device manufacturing were identified to be(1) the step of manually mounting semiconductor wafers onto supportsubstrates and (2) the step of manually demounting the wafers from thesubstrates. The support substrates from the mounting step are used toreduce wafer breakage during wafer thinning, backside via etching, andother wafer backside processing steps. The demounting step occurs afterthe wafer backside processing steps and occurs before sawing the wafersinto individual semiconductor devices. Wafer breakage at the mountingand demounting steps is very costly because these two steps areperformed near the end of the manufacturing process after incurring mostof the manufacturing costs.

The demounting step typically involves (1) placing the support substrateand the semiconductor wafer onto a heated surface to melt the adhesivethat connects the substrate to the wafer and (2) manually pushing orsliding the wafer off of the substrate after the adhesive is melted toseparate the wafer from the substrate. The wafers are extremely fragileduring the demounting process because of the reduced wafer thicknessesafter the wafer thinning process and also because of the many thousandsof via holes after the backside via etching process. Human error duringthe manual performance of the demounting step is the main reason for thehigh incidents of wafer breakage during the demounting step.

Accordingly, a need exists for a non-manual method of demounting orseparating a semiconductor substrate from a support substrate whereinthe non-manual method does not break or otherwise fracture thesemiconductor substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 outlines a method of manufacturing semiconductor devices inaccordance with the present invention;

FIG. 2 illustrates a partial side view of an apparatus used tomanufacture semiconductor devices during a particular manufacturing stepin accordance with the present invention;

FIGS. 3 and 4 illustrate simplified partial side views of the apparatusand the semiconductor devices at later times during the manufacturingprocess in accordance with the present invention;

FIG. 5 illustrates a partial side view of an alternative embodiment ofthe apparatus of FIG. 2. in accordance with the present invention; and

FIG. 6 illustrates a partial side view of another alternative embodimentof the apparatus of FIG. 2 in accordance with the present invention.

For simplicity and clarity of illustration, elements in the drawings arenot necessarily drawn to scale. Furthermore, the same reference numeralsin different Figures denote the same elements.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 outlines a method 100 of manufacturing semiconductor devices.Method 100 includes a step 101 for fabricating a first portion of asemiconductor device into a first surface of a semiconductor substrateor wafer. Step 101 includes doping regions of the first surface of thesemiconductor substrate to form transistors, diodes, resistors, and thelike. Step 101 can also include forming a multi-layer metallizationscheme over the first surface of the semiconductor substrate to form anintegrated circuit. Therefore, although the term semiconductor substrateis used hereinafter, it is understood that the semiconductor substratecan include non-semiconductor layers.

Method 100 continues with a step 102 for mounting the semiconductorsubstrate onto a support substrate or wafer. Step 102 includes using anadhesive to mount, attach, or otherwise couple the semiconductorsubstrate to the support substrate. In the preferred embodiment, thefirst surface of the semiconductor substrate faces towards and iscovered by the adhesive and the support substrate while a second andopposite surface of the semiconductor substrate faces away from thesupport substrate and remains exposed. The adhesive comprises anymaterial that is capable of withstanding elevated temperatures of up toapproximately two hundred degrees Celsius during subsequent processingof the second surface of the semiconductor substrate. Examples ofsuitable adhesives include wax, photoresist, and double-sided tape.

After completing step 102, method 100 proceeds with a step 103 forfabricating a second portion of the semiconductor device into the secondsurface of the semiconductor substrate while the semiconductor substrateremains attached to the support substrate. The fabrication process ofstep 103 includes, for example, thinning the semiconductor substratefrom approximately six hundred twenty-five micrometers to a thickness ofapproximately one hundred to twenty-five micrometers, etching sourcevias into the second surface, or depositing a metal into the source viasand onto the second surface of the semiconductor substrates. Thethinning process often also reduces the diameter of the semiconductorsubstrate by a few millimeters.

Next, a step 104 exposes the semiconductor substrate and the supportsubstrate to at least one chemical to separate the semiconductorsubstrate from the support substrate. Step 104 can be performed byinserting the semiconductor wafer and the support substrate into a wafercassette while the semiconductor substrate remains attached to thesupport substrate. Then, the semiconductor substrate, the supportsubstrate, and the wafer cassette can be submerged into a first solutionto dissolve, melt, soften, or at least weaken the adhesive and toseparate or release the semiconductor substrate from the supportsubstrate. The substrates and the wafer cassette can be placed into atank already filled with the first solution, or the substrates and thewafer cassette can be placed into an empty tank, which is later filledwith the first solution.

The first solution can be a solvent or any other chemical thatdissolves, melts, softens, or at least weakens the adhesive. In thepreferred embodiment, the first solution does not substantially etch orotherwise attack the semiconductor substrates, the support substrates,or the wafer cassette. The first solution can be heated to reduce thetime required to removed the semiconductor substrate from the supportsubstrate. Furthermore, the first solution can be used simultaneouslywith an ultrasonic device to further improve the cycle time of step 104.

The first solution is preferably filtered during step 104 to removecontaminants from the first solution. A static bath is undesirablebecause of the resulting significant increase in the cycle time of step104. However, the filtration of the first solution should not create asubstantial amount of turbulence to ensure that the semiconductorsubstrate is not washed out of the wafer cassette.

Step 104 can also include subsequently submerging the semiconductorwafer into a second solution after the first submerging step.Preferably, the second submerging step occurs after the semiconductorsubstrate is already separated from the support substrate during thefirst submerging step. Also in the preferred embodiment, at least ninetyto ninety-five percent of the adhesive is dissolved prior to the secondsubmerging step. Furthermore, the first and second solutions preferablyconsist essentially of the same or similar chemical or chemicals. Thesecond submerging step is used to ensure that the adhesive is completelyremoved from the first surface of the semiconductor substrate. Thesecond solution can also be heated and can simultaneously be used withan ultrasonic device to reduce the cycle time of step 104. In anembodiment where photoresist is used for the adhesive, the secondsolution is preferably heated to a lower temperature than the firstsolution.

Method 100 continues with a step 105 for cleaning the semiconductorsubstrate. Step 105 can include, among other steps, rinsing thesemiconductor substrate with deionized water or alcohol to remove thefirst and second solutions from the semiconductor substrate. If thedeionized water is not heated to a similar temperature as the firstsolution or second solution, then the semiconductor substrates should beallowed to cool for several seconds prior to being cleaned in step 105.This short waiting period of approximately five to thirty-five secondsreduces the possibility of fracturing the semiconductor substrates dueto thermal shock.

Then, a step 106 can be performed to dry the semiconductor substratewith a flow of gaseous nitrogen, argon, or the like. Preferably, step106 does not spin or otherwise set the semiconductor substrate on itsedge because of the fragility of the thinned semiconductor substrate.

Method 100 continues with a step 107 for sawing the semiconductorsubstrate to remove or excise the semiconductor device from thesemiconductor wafer. The semiconductor device can then be packaged usingmethods known to those skilled in the art.

FIG. 2 illustrates a partial side view of an apparatus 210 used tomanufacture semiconductor devices during step 104 of method 100 inFIG. 1. Apparatus 210 is a cassette for holding a plurality ofsemiconductor wafers or substrates 224. Apparatus 210 includes walls 216and 217 that are substantially parallel to each other. A third wall 218is substantially perpendicular to both of walls 216 and 217 and couplestogether walls 216 and 217. Walls 216 and 217 each have a plurality orset of protrusions or tabs 212 and 214. In the preferred embodiment,apparatus 210 is identical to a conventional wafer cassette, except thateach of tabs 212 are approximately one to three millimeters shorter thanthose of a conventional wafer cassette for reasons explainedhereinafter.

Tabs 212 and 214 of wall 216 extend from wall 216 toward wall 217, andtabs 212 and 214 of wall 217 extend from wall 217 toward 216. Tabs 212and 214 of wall 216 are separated from and do not physically contactwall 217, and tabs 212 and 214 of wall 217 are separated from and do notphysically contact wall 216. Additionally, tabs 212 and 214 aredifferent from each other. In particular, tabs 212 of wall 216 areshorter than tabs 214 of wall 216, and tabs 212 of wall 217 are shorterthan tabs 214 of wall 217. Furthermore, tabs 214 of wall 216 are locatedbetween adjacent tabs 212 of wall 216, and tabs 214 of wall 217 arelocated between adjacent tabs 212 of wall 217. Moreover, as illustratedin FIG. 1, one of tabs 212 of wall 216 is closer to wall 218 than any oftabs 214 of walls 216, respectively, and one of tabs 212 of wall 217 iscloser to wall 218 than any of tabs 214 of walls 217, respectively.

In the preferred embodiment, tabs 212 of walls 216 and 217 are haveapproximately equal lengths and are substantially identical to eachother, and tabs 214 of walls 216 and 217 have approximately equallengths and are substantially identical to each other. Furthermore, eachof tabs 212 of wall 216 is preferably substantially coplanar with one oftabs 212 of wall 217, and each of tabs 214 of wall 216 is preferablysubstantially coplanar with one of tabs 214 of wall 217. Also in thepreferred embodiment, tabs 212 and 214 are all substantially parallelwith each other and with wall 218. Moreover, the spacing between wall218 and the first ones of tabs 212 of walls 216 and 217 is preferablythe same as the spacing between any of adjacent tabs 212 and 214 of wall216 and is also preferably the same as the spacing between any ofadjacent tabs 212 and 214 of wall 217.

Semiconductor substrates 224 have a first major surface 225 opposite asecond major surface 226. Portions of semiconductor devices 227 havebeen previously formed in surfaces 225 during step 101 of method 100 inFIG. 1. As discussed earlier, substrates 224 can include dielectric,metal, and other layers over surfaces 225.

Substrates 224 are coupled to support substrates 220 wherein surfaces225 of substrates 224 face towards substrates 220 while surfaces 226 ofsubstrates 224 remain exposed. Each of substrates 220 are preferablycomprised of an optically transparent substrate to facilitate theprocessing of surface 226 during step 103 of method 100 in FIG. 1. Inparticular, the optically transparent characteristic of substrate 220enables the location of alignment keys on surface 225 of substrate 224.As an example, substrates 220 can be comprised of quartz or sapphire.Substrates 220 are larger than substrates 224 by preferably about one tothree millimeters before step 103 of method 100 in FIG. 1. Substrates220 also preferably have a plurality of holes 221 therethrough forreasons explained hereinafter.

Adhesives 222 are located between substrates 220 and 224 to couplesubstrates 220 and 224 together. As described earlier, adhesives 222 canbe comprised of wax, photoresist, double-sided tape, or the like. In thepreferred embodiment, adhesives 222 are preferably optically transparentfor the same reasons as described earlier for substrate 220.

After substrates 220 and 224 are coupled together with adhesives 222,substrates 220 and 224 and adhesives 222 are subjected to step 103 ofmethod 100 in FIG. 1. Then, substrates 220 and 224 are simultaneouslypositioned, inserted, or otherwise disposed into apparatus 210 abovetabs 212. As illustrated in FIG. 1, tabs 212 of walls 216 and 217support substrates 220 and 224. However, tabs 212 preferably onlycontact substrates 220 and preferably do not contact substrate 224 sothat tabs 212 do not hinder the subsequent separation of substrates 220and 224. To prevent tabs 212 from contacting substrate 224, the shortestdistance between walls 216 and 217 is preferably larger than thediameter of substrate 220 by a distance of at least one millimeter; theshortest distance between the distal ends of tabs 212 is preferablylarger than the diameter of substrate 224 by at least the same distance;and substrate 224 is preferably mounted in the middle of or concentricwith substrate 220.

Tabs 212 separate substrates 220 and 224 from support substrates 228,which are supported by tabs 214 of walls 216 and 217. At this point inthe process, tabs 214 do not support either of substrates 220 or 224,and tabs 214 and 212 separate each of substrates 228 from each ofsubstrates 220 and 224. Substrate 228 preferably has a roughed surfacefacing towards overlying substrate 224 for reasons explainedhereinafter. As an example, substrate 228 can be comprised of silicon,sapphire, TEFLON® material manufactured by DuPont Corporation ofWilmington, Del., or the like.

After substrates 220, 224, and 228 are positioned within apparatus 210,apparatus 210 is positioned such that each of tabs 214 are positionedbelow at least one of tabs 212. Thus, as illustrated in FIG. 2, tabs 212support substrates 220 and 224; tabs 214 support substrates 228; and themajor surfaces of substrates 220, 224, and 228 are substantiallyperpendicular to the force of gravity. While in this position,substrates 224 are exposed to at least one chemical to separate orrelease substrate 224 from substrate 220, and then gravity movessubstrate 224 away from tabs 212 and towards tabs 214 without removingsubstrate 224 from apparatus 210, as explained in more detailhereinafter.

In the preferred embodiment, apparatus 210 and substrates 220, 224, and228 are submerged into a liquid solution 201 that dissolves, melts,softens, or at least weakens adhesives 222 to separate substrates 220and 224. Solution 201 can be a solvent or other suitable chemical. Forexample, if adhesives 222 are a photoresist, then solution 201 can be aphotoresist stripper such as ST-22 manufactured by Advanced ChemicalSystems International, Incorporated in Milpitas, Calif. As anotherexample, if adhesives 222 are a wax, then solution 201 can be hot water.In the preferred embodiment, apparatus 210 and substrates 220, 224, and228 are not substantially affected by solution 201.

Holes 221 in each of substrates 220 enable solution 201 to dissolve,melt, soften, or weaken adhesives 222 from the back sides of substrates220. Thus, optional holes 221 can be used to reduce the cycle time ofstep 104 of method 100 in FIG. 1. In the preferred embodiment, onlysolution 201, gravity, and perhaps ultrasonic waves are used to separatesubstrates 220 and 224.

FIG. 3 illustrates a simplified partial side view of apparatus 210 andsubstrates 220, 224, and 228 at a later time during step 104 of method100 in FIG. 1. Tank 200 and solution 201 are not illustrated in FIG. 3to simplify the explanation of the present invention. The present Figureillustrates the preferred embodiment where adhesive 222 of FIG. 2 asalready been substantially dissolved and where substrate 224 is releasedfrom substrate 120. In FIG. 3, gravity moves substrate 224 away fromtabs 212, away from substrate 220, and downward towards adjacent tabs214 and substrate 228 without removing substrate 224 from apparatus 210.This downward movement is achieved by ensuring that the distance betweentabs 212 is at least slightly larger than the diameter of substrate 224.In the preferred embodiment, only gravity is used to produce thedownward movement of substrate 224. As illustrated in FIG. 3, substrates220 and 228 remain supported by tabs 212 and 214, respectively, duringthe descent of substrate 224.

FIG. 4 illustrates a simplified partial side view of apparatus 210 andsubstrates 220, 224, and 228 at an even later time during step 104 ofmethod 100 in FIG. 1. Tank 200 and solution 201 are not illustrated inFIG. 4 to simplify the explanation of the present invention. Afterfalling from tabs 212, substrate 224 overlies and is supported bysubstrate 228, which is supported by tabs 214. Substrate 228 is locatedbetween tabs 214 and substrate 224 so that tabs 214 do not directlycontact substrate 224. Thus, substrate 224 is no longer supported bytabs 212.

Then, apparatus 210 is removed from tank 200 and solution 201. In oneembodiment, as described earlier with reference to steps 104, 105, and106 of method 100 of FIG. 1, apparatus 210 and substrates 220, 224, and228 can be submerged into a second solution or filtered bath, andsubstrates 224 can also be cleaned and dried. However, these subsequentsteps preferably keep surfaces 225 and 226 of substrate 224substantially perpendicular to gravity in order to reduce theprobability of chipping or otherwise damaging the edges of substrate224, which is extremely thin after step 103 in method 100 of FIG. 1.

Eventually, substrate 228 is removed out of apparatus 210 whilesubstrate 224 rests on substrate 228. Then, substrate 224 is removedfrom substrate 228. In one embodiment, one-sided tape is placed ontosubstrate 224 to lift substrate 224 off of substrate 228. This one-sidedtape is then also used to support substrate 224 during the wafer sawingprocess of step 107 in FIG. 1. The aforementioned rough surface ofsubstrate 228 facilitates the removal of substrate 224 from substrate228 by eliminating or at least reducing the hydroscopic andelectrostatic forces between substrates 224 and 228. This surface ofsubstrate 228 can also have bumps, holes, or other features to furtherfacilitate the removal of substrate 224 from substrate 228. Only onesurface of substrate 228 is required to have this rough or non-smoothcharacteristic.

FIG. 5 illustrates a partial side view of an apparatus 510, which is analternative embodiment of apparatus 210 in FIG. 2. In the preferredembodiment, apparatus 510 has walls 516, 517, and 518, which areidentical to walls 216, 217, and 218, respectively, of apparatus 210 inFIG. 2. Apparatus 510 also has protrusions or tabs 512 and 514, whichare preferably similar to tabs 212 and 214, respectively, of apparatus210. In this preferred embodiment, apparatus 510 is the same as aconventional wafer cassette, except that tabs 512 are a few millimetersshorter than the tabs of a conventional wafer cassette and except thattabs 512 have grooves, keys, slots, or notches 513 at their distal ends.With this configuration of tabs 512, substrates 220 are positioned innotches 513 and in between tabs 512, instead of above tabs 212, asillustrated in FIG. 2.

FIG. 6 illustrates a partial side view of an apparatus 610, which isanother alternative embodiment of apparatus 210 in FIG. 2. In thepreferred embodiment, apparatus 610 has walls 616, 617, and 618, whichare identical to walls 216, 217, and 218, respectively, of apparatus 210in FIG. 2. Apparatus 610 also has protrusions or tabs 612 and 614, whichare preferably similar to tabs 212 and 214, respectively, of apparatus210. In this preferred embodiment, apparatus 610 is the same as aconventional wafer cassette, except that tabs 612 and 614 are shorterthan the tabs of a conventional wafer cassette and except that each oftabs 612 and 614 have grooves, keys, slots, or notches 613 and 615 attheir respective distal ends. Tabs 612 and 614 can be the same length.With this configuration of tabs 612 and 614, substrates 220 arepositioned in notches 613 and in between tabs 612, instead of above tabs212, as illustrated in FIG. 2, and substrates 228 are positioned innotches 615 and in between tabs 614, instead of above tabs 214, asillustrated in FIG. 2.

Therefore, an improved method of manufacturing a semiconductor deviceand apparatus thereof is provided and overcomes the disadvantages of theprior art. The method of manufacturing automates a previously manualprocess for demounting wafers and reduces the high rates of waferbreakage due to human error. Additionally, the manufacturing methoddescribed herein is faster than the previous manual process. Forinstance, a single person can simultaneously process a batch of wafers,whereas under the previous manual process, a single person can onlyprocess a single wafer at a time. Moreover, when the wafer cassettesdescribed herein are similar to conventional wafer cassettes, theconventional wafer cassettes can be inexpensively and quickly modifiedto practice the automated demounting process described herein.

While the invention has been particularly shown and described mainlywith reference to preferred embodiments, it will be understood by thoseskilled in the art that changes in form and detail may be made withoutdeparting from the spirit and scope of the invention. For instance, thenumerous details set forth herein such as, for example, the specificchemical compositions and dimensions are provided to facilitate theunderstanding of the present invention and are not provided to limit thescope of the invention. As another example, the use of substrate 228 isoptional if tabs 214, 514, or 614 are long enough to support substrate224 after being separated from substrate 220. However, the use ofsubstrate 228 is preferred because of the pressure exerted uponsubstrate 224 when substrate 224 and apparati 210, 510, and 610 areremoved from solution 201.

Furthermore, tabs 214, 514, and 614 and substrates 228 can be completelyeliminated from apparati 210, 510, and 610. In this embodiment,substrates 224 simply fall down to rest on the back surface of a lowersupport substrate 220. In a different embodiment which still eliminatestabs 214, 514, and 614 and substrates 228, substrates 220 and 224 can beplaced upside down within apparati 210, 510, and 610. For example, inFIG. 2, substrates 224 would now be located above tabs 212 instead ofbetween tabs 212. In this embodiment, substrates 224 do not move afteradhesive 222 is dissolved, which may help reduce wafer breakage.However, this embodiment makes the complete and thorough removal ofadhesive 222 from surface 225 of substrate 224 much more difficult.

As another alternative embodiment, any suitable gas, vapor, or liquidchemical can be used for solution 201 to dissolve adhesive 222. However,the use of a liquid for solution 201 is preferred to reduce the velocityat which substrate 224 falls or floats towards substrate 228. Byreducing the velocity, substrate 224 is less likely to break.

Moreover, a retaining mechanism can be added to apparati 210, 510, and610 after inserting substrates 220, 224, and 228 to ensure that thesubstrates do not fall out of the apparati during the demounting processof step 104 in FIG. 1. This configuration of apparati 210, 510, and 610is especially useful when the filtering of solution 201 causes asignificant amount of turbulence.

Accordingly, the disclosure of the present invention is not intended tobe limiting. Instead, the disclosure of the present invention isintended to be merely illustrative of the scope of the invention, whichis set forth in the following claims.

What is claimed is:
 1. A method of manufacturing a semiconductor devicecomprising:providing an apparatus having a tab; physically coupling asemiconductor substrate to a support substrate; inserting thesemiconductor substrate and the support substrate into the apparatus;supporting the semiconductor substrate above the tab; separating thesemiconductor substrate from the support substrate; and moving thesemiconductor substrate towards the tab while keeping the semiconductorsubstrate in the apparatus.
 2. The method of claim 1 furthercomprising:providing the semiconductor substrate coupled to a supportsubstrate; and inserting the semiconductor substrate coupled to thesupport substrate into the apparatus wherein the first one of the tabscontacts and supports the support substrate and wherein the second oneof the tabs is devoid of supporting the semiconductor substrate, whereinproviding the apparatus further comprises providing the apparatus with atabs for supporting semiconductor substrates wherein a first one of thetabs is located above a second one of the tabs.
 3. The method of claim 2wherein the providing step further comprises providing the supportsubstrate comprised of an optically transparent substrate with holes,and wherein the inserting step further comprises preventing the firstone of the tabs from contacting the semiconductor substrate.
 4. Themethod of claim 2 wherein the inserting step further comprisessimultaneously using the first one and a third one of the tabs tosupport the semiconductor substrate wherein a distance between the firstand third ones of the tabs is larger than a diameter of thesemiconductor substrate.
 5. The method of claim 4 wherein thesimultaneously using step further comprises positioning the supportsubstrate above the first and third ones of the tabs to support thesemiconductor substrate.
 6. The method of claim 4 wherein thesimultaneously using step further comprises positioning the supportsubstrate between the first and third ones of the tabs to support thesemiconductor substrate.
 7. The method of claim 2 wherein the movingstep further comprises moving the semiconductor substrate toward thesecond one and a third one of the tabs without removing thesemiconductor substrate from the apparatus wherein a distance betweenthe second and third ones of the tabs is smaller than a diameter of thesemiconductor substrate.
 8. The method of claim 2 further comprisingsupporting the semiconductor substrate with a support substrate in theapparatus wherein the support substrate is supported by the second oneof the tabs before, during, and after the moving step, and wherein thesupport substrate is located between the second one of the tabs and thesemiconductor substrate.
 9. The method of claim 1 wherein the insertingstep occurs after the physically coupling step and further comprisessimultaneously inserting the semiconductor substrate and the supportsubstrate into the apparatus,wherein the supporting step occurs afterthe inserting step and further comprises supporting the supportsubstrate above the protrusion, wherein the separating step occurs afterthe supporting step, and wherein the moving step occurs after theseparating step and further comprises moving the semiconductor substrateaway from the support substrate, keeping the support substrate above theprotrusion, and positioning a major surface of the semiconductorsubstrate substantially perpendicular to gravity wherein the gravitymoves the semiconductor substrate towards the tab.
 10. A method ofmanufacturing a semiconductor device comprising:mounting a semiconductorsubstrate onto a support substrate; providing an apparatus having aplurality of protrusions wherein a length of a first one of theplurality of protrusions is shorter than a length of a second one of theplurality of protrusions; positioning the semiconductor substrate andthe support substrate into the apparatus wherein the first one of theplurality of protrusions supports the support substrate and thesemiconductor substrate; exposing the semiconductor substrate to achemical to release the semiconductor substrate from the supportsubstrate; and moving the semiconductor substrate from the first one ofthe plurality of protrusions towards the second one of the plurality ofprotrusions while the support substrate remains supported by the firstone of the plurality of protrusions.
 11. The method of claim 10 whereinthe providing step further comprises providing the first and second onesof the plurality of protrusions adjacent to each other and wherein thepositioning step further comprises preventing the first and second onesof the plurality of protrusions from contacting the semiconductorsubstrate.
 12. The method of claim 10 wherein the moving step furthercomprises using gravity to move the semiconductor substrate from thefirst one of the plurality of protrusions toward the second one of theplurality of protrusions.
 13. The method of claim 10 wherein themounting step includes providing the semiconductor substrate with amajor surface and wherein the exposing and moving steps furthercomprise:positioning the major surface substantially perpendicular to aforce of gravity; and positioning the second one of the plurality ofprotrusions underneath the first one of the plurality of protrusions andbelow the semiconductor substrate.
 14. The method of claim 10 furthercomprising using the second one of the plurality of protrusions tosupport the semiconductor substrate after the moving step wherein thesupport substrate remains supported by the first one of the plurality ofprotrusions during and after the moving step and wherein the supportsubstrate is devoid of being supported by the second one of theplurality of protrusions during and after the moving step.
 15. A methodof manufacturing a semiconductor device comprising:fabricating a firstportion of the semiconductor device into a first surface of asemiconductor wafer wherein the semiconductor wafer has a second surfaceopposite the first surface; using an adhesive to attach thesemiconductor wafer to an optically transparent wafer after fabricatingthe first portion of the semiconductor device wherein the opticallytransparent wafer has holes therein, wherein the optically transparentwafer is larger than the semiconductor wafer, and wherein the firstsurface of the semiconductor wafer faces towards the opticallytransparent wafer; fabricating a second portion of the semiconductordevice into the second surface of the semiconductor wafer while thesemiconductor wafer is attached to the optically transparent wafer;providing a plurality of wafers in a wafer cassette having tabs;inserting the semiconductor wafer into the wafer cassette while thesemiconductor wafer is attached to the optically transparent waferwherein the tabs separate the semiconductor wafer and the opticallytransparent wafer from the plurality of wafers in the wafer cassette andwherein the semiconductor wafer is devoid of physically contacting thetabs; submerging the semiconductor wafer, the optically transparentwafer, the plurality of wafers, and the wafer cassette in a firstsolution to dissolve the adhesive and to separate the semiconductorwafer from the optically transparent wafer wherein the submerging stepoccurs after the two fabricating steps, wherein the first surface of thesemiconductor wafer is positioned approximately perpendicular to a forceof gravity during the submerging step, and wherein the force of gravitymoves the semiconductor wafer from a first one of the tabs towards anadjacent one of the tabs during the submerging step; cleaning thesemiconductor wafer after the submerging step; drying the semiconductorwafer after the cleaning step; and sawing the semiconductor wafer toremove the semiconductor device from the semiconductor wafer after thedrying step.
 16. The method of claim 15 further comprising submergingthe semiconductor wafer into a second solution after submerging thesemiconductor wafer into the first solution and before the cleaning stepwherein the second submerging step occurs after the semiconductor waferis separated from the optically transparent wafer and wherein the firstand second solutions consist essentially of similar chemicals.
 17. Themethod of claim 16 wherein the first submerging step includes heatingthe first solution to a first temperature and wherein the secondsubmerging step includes heating the second solution to a secondtemperature lower than the first temperature.
 18. The method of claim 15wherein the submerging step further comprises using an ultrasonicprocess simultaneously with the first solution to separate thesemiconductor wafer from the optically transparent wafer.
 19. The methodof claim 15 wherein the drying step includes preventing thesemiconductor substrate from spinning.
 20. The method of claim 15further comprising using a support substrate to support thesemiconductor wafer during the submerging step wherein the supportsubstrate is supported by the adjacent one of the tabs wherein theadjacent one of the tabs is devoid of supporting the semiconductor waferduring the inserting step.
 21. An apparatus for manufacturing asemiconductor device comprising a cassette for holding a plurality ofsemiconductor substrates wherein the cassette hasfirst and secondopposing walls; and a plurality of protrusions for separating theplurality of semiconductor substrates, wherein a first protrusion of afirst set of the plurality of protrusions extends from the first walland a second protrusion of the first plurality of protrusions extendsfrom the second wall and wherein each protrusion of the first set of theplurality of protrusions has a first length, a first protrusion of asecond set of the plurality of protrusions extends from the first walland a second protrusion of the second plurality of protrusions extendsfrom the second wall and wherein each protrusion of the second set ofthe plurality of protrusions has a second length, the second length lessthan the first length, and a first protrusion of a third set of theplurality of protrusions extends from the first wall and a secondprotrusion of the third plurality of protrusions extends from the secondwall and wherein each protrusion of the third plurality of protrusionshas a third length, the third length greater than the second length andwherein the first protrusion of the second set of the plurality ofprotrusions is located between the first protrusions of the first andthird sets of the plurality of protrusions and the second protrusion ofthe second set of the plurality of protrusions is located between thesecond protrusions of the first and third sets of the plurality ofprotrusions.
 22. An apparatus for manufacturing a semiconductor devicecomprising:a first wall; a second wall substantially parallel to thefirst wall and coupled to the first wall; a first set of tabs coupled tothe first wall and extending from the first wall towards the second wallwherein a first tab of the first set of tabs is shorter than a secondtab of the first set of tabs and wherein the first and second tabs ofthe first set of tabs are adjacent to each other; and a second set oftabs coupled to the second wall and extending from the second walltoward the first wall wherein a first tab of the second set of tabs isshorter than a second tab of the second set of tabs, wherein the firstand second tabs of the second set of tabs are adjacent to each other,wherein the first tabs of the first and second set of tabs haveapproximately equal lengths and are substantially coplanar with eachother, wherein the second tabs of the first and second set of tabs haveapproximately equal lengths and are substantially coplanar with eachother, and wherein the first and second tabs of the first and second setof tabs are substantially parallel with each other.
 23. The apparatus ofclaim 22 further comprising a third wall coupling the first and secondwalls together wherein the third wall is substantially parallel to thefirst and second set of tabs, wherein the first tabs of the first andsecond set of tabs are closer to the third wall than the second tabs ofthe first and second set of tabs, and wherein a first distance betweenthe third wall and the first tab of the first set of tabs isapproximately equal to a second distance between the third wall and thefirst tab of the second set of tabs and is approximately equal to athird distance between the first and second tabs of the first set oftabs and is approximately equal to a fourth distance between the firstand second tabs of the second set of tabs,wherein the first set of tabsfurther comprises:a third tab adjacent to the second tab of the firstset of tabs and having a length approximately equal to the first tab ofthe first set of tabs; and a fourth tab adjacent to the third tab of thefirst set of tabs and having a length approximately equal to the secondtab of the first set of tabs wherein the third tab of the first set oftabs is located between the second and fourth tabs of the first set oftabs, wherein the second set of tabs further comprises:a third tabadjacent to the second tab of the second set of tabs and having a lengthapproximately equal to the first tab of the second set of tabs whereinthe third tab of the second set of tabs is approximately coplanar withthe third tab of the first set of tabs; and a fourth tab adjacent to thethird tab of the second set of tabs and having a length approximatelyequal to the second tab of the second set of tabs wherein the fourth tabof the second set of tabs is approximately coplanar with the fourth tabof the first set of tabs and wherein the third tab of the second set oftabs is located between the second and fourth tabs of the second set oftabs, wherein the first set of tabs is physically separated from thesecond wall, wherein the second set of tabs is physically separated fromthe first wall, and wherein the first and second tabs of the first andsecond set of tabs have notches at their distal ends.